Re. Steinpreis et al., THE EFFECTS OF CYPROHEPTADINE ON VACUOUS JAW MOVEMENTS IN RATS - A COMPARISON WITH HALOPERIDOL AND CLOZAPINE, Psychopharmacology bulletin, 32(1), 1996, pp. 129-134
Classic neuroleptics produce a syndrome of vacuous jaw movements in ra
ts, hut atypical neuroleptics such as clozapine do not, This syndrome
has been offered as a rapid and inexpensive means of assaying novel an
tipsychotic compounds for the production of early onset extrapyramidal
side effects, Cyproheptadine is a serotonergic antagonist that has be
en suggested for the treatment of schizophrenia, The present study com
pared the effects of repeated administration of cyproheptadine with th
ose of the classic antipsychotic haloperidol and the atypical antipsyc
hotic clozapine in terms of their production of vacuous jaw movements.
Rats were administered either tartaric acid vehicle or one of three d
oses of each drug daily for a month. Once a week the rats were observe
d for a B-minute period by two trained observers who recorded their va
cuous jaw movements, Cyproheptadine produced elevations in vacuous jaw
movements similar to those produced by haloperidol, but clozapine did
not. These results indicate that cyproheptadine may be similar to cla
ssic antipsychotics in the production of extrapyramidal symptoms in hu
mans, and they underscore the usefulness of the vacuous jaw movement m
odel of early onset extrapyramidal side effects.